The present invention relates to an image forming apparatus that operates on the basis of electrophotographic technology, such as a copying machine, a printer and a fax machine; and, more particularly, the invention relates to an image forming apparatus for obtaining a color image by superimposing multi-color toner images on an endless intermediate transfer belt.
One example of a known image forming apparatus using an intermediate transfer unit is a field sequential type image forming apparatus wherein, by repeating a series of processes which consist of forming a toner image on a photosensitive drum serving as a first image carrier and performing a primary transfer of this toner image on the intermediate transfer drum, four or five toner images are superimposed on the intermediate transfer drum, whereby multiplex image transfer is carried out. These steps are followed by secondary collective transfer of four or five toner images onto a transfer material, thereby obtaining a color image (or multi-color image) on the transfer material.
Such an image forming apparatus using an intermediate transfer unit is known to be capable of face-down stacking (sequential stacking with the recording surface facing downward), without the need for a special operation changing the paper position, wherein a paper back vacuuming type feed mechanism is used in the transfer material feed path (hereinafter referred to as “paper feed path”) from a transfer section to a fixing section.
As shown in FIG. 4, the paper feed path, which extends from the feed section to the fixing section, is typically almost straight in the section which leads up to the image transferring stage. (For example, see the below-listed Patent Document 1). In FIG. 4, the apparatus includes an intermediate transfer belt 6, a secondary opposite transfer roller 6a over which the belt 6 passes, a secondary transfer roller 8, a fixing device 10, including a fixing roller lOa, a pressure roller 10b and a vacuum feed section 11.
Patent Document 1: Japanese Application Patent Laid-Open Publication No. Sho 63-240577